1. Field of the Invention
This invention relates to an information recording/reproducing device, such as, a magnetic recording device or an optical recording device, and more particularly to an information recording/reproducing device having a reduced cross sectional configuration and a miniaturized design for use in compact computers systems or other such devices, for example, laptop computers.
2. Description of the Prior Art
The most typical information recording/reproducing device utilized at the present time is a magnetic recording/reproducing device, which contains a loading/unloading mechanism for receiving a recording medium inserted through a medium inlet or slot for placement of the medium inside the device and discharge of the recording medium from the device in response to a computer command or an externally applied command, a medium support section in a medium driving mechanism located on one side of the recording medium, and a clamping mechanism equipped with a collet which clamps the recording medium to the medium support section through a center hole in the medium. A conventional clamping mechanism for such an information recording/reproducing device is shown in Japanese Utility Model Laid-Open No. 174052/1986 and illustrated, in part, in FIG. 12, wherein conical collet section 1110 is provided at one end of rotational shaft 1101 and is positioned in a central opening or hole of the medium. At the other end of shaft 1101 is indent 1111 in which is placed ball 1102. Ball 1102 is retained in indent 1111 by the force of spring 1103, which forcibly retains conical section 1101 in the medium hole during rotation of the collet by hub 1112. Variations of collet structures are shown in FIGS. 13 and 14. In FIGS. 13 and 14, the clamping mechanism is provided with a hollow body collet 1106 or 1107 with corresponding springs 1108 and 1109 for forcibly coupling of the collet structure with its respective shaft 1104 or 1105 so that the collet will be in rotational relationship with the shaft upon rotation of the clamped recording medium and hub 1112. These structures are disclosed in more detail, respectively, in Japanese Utility Model Laid-Open No. 37944/1989 and Japanese Patent Laid-Open No. 177052/1990.
However, with respect to these types of clamp mechanisms, a number of parts are utilized, including the addition of a collet stop ring, as assembled, and rendering it difficult to miniaturize such a structure from both a mechanical operational and structural sense as well as being incapable of reduced in cross sectional configuration to design a more compact disc drive. Moreover, due to the number of parts that are required for assembly, the assembly of such mechanisms is labor intensive and time consuming. Also, a high degree of dimensional accuracy is required for each part for precision fitting in their assembled relationship and for continuous reliable operation.
FIGS. 15 and 16 illustrate a conventional interlocking loading/unloading mechanism and a magnetic head lifting and lowering mechanism in a conventional information recording/reproducing device, which are shown in detail in Japanese Patent Publication No. 21263/1992. These mechanisms comprise slide member 2104, having exposed operating portion 2106 on one end of the member, which is provided on a base support (not shown) so that member 2104 can move back and forth on the base support. Pin member 2104B is provided at the other end of side member 2104 for interengagement with trigger member 2107. Clamping member 2108 is rotatable about horizontal rod shaft 2112, and has collet 2108B for insertion in medium hole 2105A of medium 2105. Also, magnetic head 2118 is supported on carriage arm 2117 which is moved radially indexed relative to the radial extent of recording medium 2105.
When magnetic recording medium 2105 is inserted into the recording/reproducing device, trigger member 2107 is rotated in the direction indicated by arrow M in FIG. 15. As a result, slide member 2104 is released from trigger member 2107 and, therefore, member 2104 slides in the direction indicated by arrow N due to the tension of spring 2110. Roller 2104C on slide member 2104, in turn, pushes cam 2108A of clamping member 2108 upwardly so that clamping member 2108 is rotated about shaft 2112 in the direction indicated by arrow P and, as a result, magnetic recording medium 2105 is clamped by collet 2108B due to its insertion into medium hole 2105A.
Relative to carriage arm 2117, connecting bar 2117A is supported by arm portion 2108C of clamping member 2108. Therefore, as arm portion 2108C descends with the engagement of collet on medium 2105, carriage arm 2117 is also lowered, and magnetic head 2118 of arm 2117 comes into engagement with the surface of magnetic recording medium 2105.
In the connection with the lowering of clamping member 2108, member 2108 is generally biased in an upward direction, indicated by arrow Q, by means of spring 2109. However, the center of gravity of clamping member 2108 is offset relative to rotational point so that the member can pass a point of rotation where its weight sufficiently counteracts the force of spring 2109. Thus, if initially sufficient force is applied to clamping member 2108 when magnetic recording medium 2105 is absent from the device, member 2108 has a tendency to rotate in direction P on account of its own weight, i.e., it is sufficiently counterbalanced against the force of spring 2109, so that carriage arm 2117 will also rotate in direction P. As a result, magnetic head 2118, generally comprised of a ceramic material, may accidentally bump or make contact against its companion magnetic head, positioned in opposite facing relationship to head 2118 (not shown), resulting in head damage. If data recording is subsequently performed upon insertion of magnetic recording medium 2105 when the magnetic head has so damaged, the medium recording surface may be damaged as well. As a result, recorded data will be correspondingly destroyed or, otherwise, rendered in unreadable form. Because of this problem, a locking mechanism may be provided for locking clamping member 2108 into position to prevent its movement when medium 2105 has not been inserted into the device. Such a locking mechanism requires additional parts in the load/unload mechanism, which, of course, requires additional assembly. With more assembled parts, it is difficult to imagine any possibility of further miniaturization of these disc drives, let alone rendering them of thinner cross sectional contour for more compact, value added assembly, e.g., in a small laptop-type of computer assembly. Moreover, additional time is required for assembly rendering the resulting device more labor intensive and of greater manufacturing cost.
Relative to another aspect of an information recording/reproducing device, the rotational position of the recording medium is generally detected by detected timing based upon the employment of a timing hole formed in the magnetic recording medium which passes between a light source and a light detector. Such a standard position detection mechanism is illustrated in FIG. 17, and comprises light emitter 3129 and photodetector 3128, respectively, positioned in opposed facing relation respectively beneath and above recording medium 3105, which is rotated by motor 3103. The arrangement of light emitter 3129 beneath medium 3105, however, requires the maintenance of sufficient space at this location relative to motor 3103 to provide physical space for containing emitter 3129. Thus, miniaturization and cross sectional reduction of the device cannot be realized without some way of eliminating or otherwise reducing the requirement for this emitter space.
As shown in FIG. 17, hub 3103B and rotor 3103A of motor 3103 provide for rotational movement of magnetic recording medium 3105. When these two components are respectively positioned in the upper and lower portions of chassis 3121, it is possible to maintain sufficient space for light emitter 3129 in a portion of chassis 3121. However, in order to miniaturize the size of the device and reduce the height of motor 3103 as well as simplify the assembly process, both hub 3103B and rotor 3103A may be placed on the same chassis surface with rotor 3103A positioned directly beneath and in close proximity to magnetic recording medium 3105. However, the required space for emitter 3129 is eliminated by such a design. A solution for this shown in FIG. 18 wherein light emitter 3129 and photodetector 3128 are positioned on the same or upper side of magnetic recording medium 3105. In this arrangement, detection of the rotational passage of detection hole 3105A is determined by the difference between the level of reflecting light from the surface of the magnetic recording medium 3105 as compared to reflecting light from opening or hole 3105A. In this configuration, however, the rotational passage of detection hole 3105A cannot guaranteed 100% detection due to different and varying surface conditions of the magnetic recording medium. As a result, reliability of this timing approach is not fully effective.
Thus, a principal object of the present invention is the provision of an information recording/reproducing device that takes advantage of a design that permits structural miniaturization as well as a reduction in cross sectional thickness providing for a more compact assembly with simplified assembly and a reduced number parts required in the final assembly.